1. Field of the Invention
The present invention relates to standing seam metal roofs, and more particularly but not by way of limitation, to zone dependent selection and installation of standing seam roofs.
2. Description of the Related Art
Metal panel roofs have become common architectural features for buildings. The metal panel roof is both an aesthetic feature and a functional component of such a building. The roof of a building functions to provide shelter from the natural elements of wind, sun, rain and snow, and to enclose the building interior for environmental control. Numerous types of metal panel roofs have been proposed which resist these natural elements and which allow the metal panels to expand and contract in response to changes in temperature.
The typical support structure for a metal roof includes purlins supported by rafters that rise from an eave to a ridge peak. The purlins are the cross members that typically are interconnected and supported by the rafters to extend the length of the building.
Roofs may be classified as shed roofs and gasket roofs. Shed roofs are roofs that shed water because gravity pulls the water down and away from panel joints more effectively than wind or capillary action propel water through the joint. On the other hand, gasket roofs provide roof joints that are made watertight by placing gasket material between the panel joints and securing the gasket in place by encapsulating the gasket material or exerting pressure upon the gasket material. Generally, low slope gasket roofs may be installed where the roof slope is less than about 1 to 48.
A problem common to all roofs is wind lift caused by wind crossing over a peak creating reduced pressure above the roof, and thus a pressure differential above and below the roof. This pressure differential results in an uplift force on the panels of a metal panel roof, causing the panels to be pulled upwardly and away from the underlying support structure. This is often the primary cause of failure for a metal panel roof.
As known in the art, standing seam roofs have been developed primarily to overcome the problems created by wind uplift, snow, rain and thermal expansion and contraction. Standing seam roof panels have interlocking sidelaps, a female sidelap of each panel engaging and locking a male sidelap of an identical side-adjacent panel. As used herein, the term side-adjacent means that a first panel is adjacent a second panel on the roof. The female sidelap and male sidelap of each panel are elevated, or standing, from a central flat or corrugated medial portion of each panel.
The panels are attached to the support structure of the roof by the use of clips and through-fasteners. Through fasteners, such as sheet metal screws, substantially fix the panels and support structure together so that no differential movement occurs between panels and the support structure. There are two types of clips, fixed clips and sliding clips. Fixed clips are metal devices that attach to the underlying support structure and to the two side-adjacent metal panels at the joint of the interlocking sidelaps of the panels. Sliding clips, also called floating-clips, are attached to the side-adjacent metal panels at the joint of the interlocking sidelaps of the panels and to the underlying support structure in such a way as to permit some differential movement between the panels and the support structure.
The interlocking engagement of the sidelaps of the metal panels provide stiffness and strength to a flexible roof structure. The use of floating clips allows the roof structure to expand and contract as a function of the coefficient of thermal expansion of the panel material, and the temperature cycles of the roof panels.
Several types of seaming processes have been developed for interlocking the sidelaps of adjacently disposed panels. Most such seaming processes involve the operation of inelastically bending or rolling portions of the female sidelap and the male sidelap in a common direction. This inelastic or plastic deformation of the sidelap portions forms interlocked joints, or locks, of varying strength. That is, the interlocked sidelaps can be rolled multiple times so as to increase their resistance against unrolling or unfurling. Generally, the more times the interlocked sidelaps are rolled or plastically deformed, the stronger the lock will be to unfurling. However, stronger locks require a corresponding increase in the cost of manpower and equipment to perform the bending or locking operation.
The quality of a particular area of the roof is a function of the type of seaming performandd between side-adjacent panels. A standing seam roof of the lowest quality is a roof in which the seam joint formed between adjacent sidelaps of the roof panels is the weakest with respect to wind uplift and is the least watertight. A standing seam roof of the highest quality is a roof in which the seam joint formed between adjacent sidelaps of the roof panels is the strongest with respect to wind uplift and is the most watertight.
In the art, sidelap seaming currently follows the practice of roll seaming adjacent sidelaps from one end of the panels to the other end of the interlocked panels. Only should the seaming machine malfunction is this practice not followed, and in such a case, the seaming is restarted at the point of malfunction and the seaming is completed as much as possible as though the malfunction had not occurred.
Many factors must be considered in the design and selection of a standing seam roof for a specific building. Of primary concern is the roof performance criteria, which may be determined by the geographic location of the building and the typical weather conditions expected during the life of the building. Modem day building codes impose many different requirements for the roof of a building. All such codes include requirements for live loads, dead loads, snow loads, wind loads and earthquake loads.
Further, it is known that different areas or zones of a roof usually experience different loadings. This is especially true with regard to the factor of uplift resulting from a wind blowing over the roof. Also, the quality of watertightness required is often more critical in some portions of a roof than in other portions of the roof, the watertightness being a major concern in the valleys of the roof.
There is also the non-utilitarian, or the aesthetic, aspect of a roof The appearance of a roof is often an important consideration when deciding the kind and amount of seaming necessary for interlocking roof panels. Generally, the less plastic deforming of the panel sidelaps, the more the roof is aesthetically pleasing.
Considering these design factors, it has been the practice in most instances to determine the most critical portion of the roof and to require that all portions of the roof meet the design parameters of the most critical portion of the roof. The result of this approach is that the design specifications for the other less demanding portions of the roof exceed that which is necessary. This approach results in an unnecessary increase in the cost of the roof. Thus, there is a need for a roof that meets the requirements of all zones of the roof, minimizes the cost of the roof and is aesthetically acceptable.
The present invention provides a metal panel roof that uses different types of seaming in different demand zones of the roof to achieve the required performance at a minimum cost, and a universal panel capable of joinder by multiple seaming options.
A metal panel roof is zone mapped for performance requirements according to the functional performance required for its demand zones. The metal panels are attached to the underlying roof support structure and elastically seamed together by a roll-and-lock seam in accordance with the seaming type assigned to each zone. Next, one determines the minimum quality of seaming that meets the minimum functional performance requirements of the multiple demand zones. Finally, one seams side-adjacent metal. panels together by the minimum quality seam necessary to meet the performance requirements of the multiple demand zones.
An object of the present invention is to provide a zone based roofing system. optimizing the quality of a standing seam roof by roof function zone identification and zone adaptation of the installation process, and a universal panel for such zone based roofing.
Other objects, features and advantages of the present invention will be apparent from the following description of the invention when read in conjunction with the accompanying drawings and claims.